PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

Given a list of names = ['Alice', 'Bob', 'Charlie'], a developer wants to create a dictionary mapping each name to its length. Which expression accomplishes this?

⚠ Common exam trap

Many exam-takers confuse the key-value order in a dictionary comprehension or forget to call `len()` as a function, leading them to pick options that either swap the mapping or use an undefined variable.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

{name: len(name) for name in names}

It uses a dictionary comprehension that iterates over each name in the list, using the name as the key and the result of `len(name)` as the value. This directly maps each name to its length, which is exactly what the developer wants.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
{len(name): name for name in names}
Why it's wrong here
This maps length to name, which is the reverse of what is needed.
✓
{name: len(name) for name in names}
Why this is correct
Correct: This comprehension creates the mapping with each name and its length.
✗
{name: len for name in names}
Why it's wrong here
This sets the value to the len function object, not its result.
✗
{name: length for name in names}
Why it's wrong here
The variable 'length' is not defined; this would raise NameError.

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PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

Why each option matters

Option-by-option breakdown

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